Patent GB-191222524-A (GB)
Title: Improvements in or relating to the Prevention of Sparking in the Control of Electric Circuits.
Inventor: PRICE WILLIAM ARTHUR
IPC: H01H9/54
Filed: 1912-10-03
Granted: 1913-10-03
Abstract: 22,524. Price, W. A. Oct. 3. [Cognate Application, 22,542/12.] Commutator switching - arrangements. - Multiphase alternating current is produced from a continuouscurrent source by commutating the connexions between the terminals of the respective circuits, those receiving the alternating current being in series relationship with the directcurrent circuit; direct current is obtained from a multiphase alternating current by similar means, but the alternating-current circuits are placed in parallel with the direct-current circuit. Sparking is avoided by using condenser connexions of the kind described in Specification 14,380/10. A two - phase alternating current is obtained between the terminals A, B and A<1>, B<1>, Fig. 5, of two alternating-current circuits W, W<1> from a direct-current potential-difference V applied to terminals C, D. The terminals mentioned are connected together and to a terminal M, as shown, by condenser connexions P, to P4 and P1<1> to P4<1> of the order referred to, and these connexions are short-circuited in the following sequence, assuming P1, P3 and P1<1>, P2<1>, P3<1>, P4<1> short-circuited to commence with : break P2<1>, P4<1> and make P2, P4 ; break P1, P3 and make P2<1>, P4<1>; break P1<1>, P3<1> and make P1, P3; break P2, P4 and make P1<1>, P3<1>, and so on. Only two condenser connexions are necessary in the modified arrangement shown in Fig. 6, a similar switching cycle being employed. A commutator is described for carrying out the circuit changes according to this Figure. Twophase alternating current is changed into a practically steady continuous current by an arrangement of circuits like Fig. 10, the alternating-current circuits W, W<1> being connected in parallel at C, D, C', D<1> to the direct-current circuit V, instead of in series as in Fig. 5. The cycle is as follows, P2<1>, P,' being made: make P1, P3 and break P2<1>, P4<1>, make P1<1>, P3<1> and break P1, P3, make P2, P, and break P1<1>, P3<1>, make P2<1>, P4<1> and break P2, P4, and so on. The condenser connexions may be reduced to four in number by the arrangement shown in Fig. 11, d, d<1>, e, e<1>, f, f<1>, g, g<1> being simple switch connexions and the cycle being as follows, assuming e<1> and g are closed: make P2, P4, d, and f<1>; break e<1>, g, P2, and P,; make P1, P3, e, and g<1>; break d, f<1>, P<1>, and P<3>; make P2, P4, d<1>, and f; break e, g<1>, P2, and P4; make P1, P3, e<1>, and g; break d<1>, f, P1, and P3, and so on. The general type of condenser connexion used is illustrated in Fig. 2. A condenser K alone is connected between the circuit terminals A, B when the circuit is open, and the circuit is closed first by the switch 1 through an inductance L and resistance It in parallel, whereby the condenser is discharged; the switch 2 is then closed to complete the discharge of the condenser; the switch 3 is finally closed so as to place a highly non-inductive circuit in shunt to the condenser. The circuit between A, B is opened sparklessly by the switches 1, 2, 3 operated in that order. The rate of discharge of the condenser K may be increased without increasing the maximum discharge current by shunting the resistance R by a lower resistance when the condenser is partly discharged.